I made them once. I had some that I bought at REI, then I copied that design. I used velcro instead of a zipper. I put a draw string at the top and used elastic at the bottom, with grommets and string to wrap around the bottom of my boots. I even used them a month ago in knee deep snow when I couldn't find the store bought ones.
I've taken a vow of poverty. To annoy me, send money.